Did you know, for example, that there are only an estimated 750 of them in the hundreds of miles of state waters.

In case you didn’t know, the greenback cutthroat trout was designated Colorado’s official state fish of Colorado in 1994, to recognize a true Colorado trout. Previously, the state fish was the rainbow trout — a fish that had been imported into Colorado in 1882.

Originally considered indigenous to many small streams and rivers throughout the Arkansas and South Platte river basins in Colorado, the greenback eventually wound up on the verge of extinction at the time of its designation, as loss of good habitat and the introduction of additional species of trout took a toll.

“We’ve known for some time that the trout in Bear Creek were unique,” said Doug Krieger, a senior aquatic biologist for Colorado Parks and Wildlife Service.

“But we didn’t realize they were the only surviving greenback population,” Krieger added.

The findings of the CU researchers, Jessica Metcalf and Andrew Martin, were startling, said Theo Stein of the service’s Denver office.

“It opened the window of this fish that surprised a lot of people. We didn’t know we’re one stream away from extinction of the state fish,” Stein said.

The number of greenback living in the four­mile reach of Bear Creek was estimated from fish sampling completed in 2011. However, the actual number could vary as sampling in these type of headwater streams can be difficult.

The study also found that a previously undiscovered San Juan Basin cutthroat and the yellowfin cutthroat trout (which was originally found in the upper basin around Leadville) also are extinct.
It has meant a change in the service’s thinking on management of the greenback.

To complement the new research findings, the Greenback Cutthroat Trout Recovery Team has begun working with Colorado State University to reexamine the physical characteristics of Colorado cutthroats. When completed, scientists will compare results from physical examination with the genetic analysis in hopes of further clarifying the evolutionary relationships among native cutthroat trout.

In the meantime, Colorado Parks and Wildlife and the U.S. Fish and Wildlife Service have begun growing a broodstock of greenback in two hatcheries with hopes of transplanting a new population back to the wild by 2014. Krieger is optimistic about the future of greenback cutthroats and suggests that, “This fish was found in many streams before settlers came to Colorado, and we hope to expand greenbacks to more places so that people can enjoy this legacy once again.”